The present invention relates to a controller of a vehicle propulsion system and, more specifically, to a controller of a vehicle propulsion system which allows a vehicle to run only by an engine by simplifying the control of the engine and an electrical motor and by improving the reliability of the control of the motor.
Among vehicles, there exists a so-called hybrid car carrying an internal combustion engine and an electric motor as power sources for its propulsion system. Such vehicle is provided with engine control means and motor control means for controlling operating conditions of the engine and the motor. In driving the vehicle, the engine control means and the motor control means detect the operating conditions of the engine and the motor, respectively, and exchange detected operation data of the engine and the motor with each other to control the operating conditions of the engine and the motor in coordination and to achieve the required performances (fuel consumption, value of detrimental components in the exhaust gas, power performance and others) to a high degree.
Examples of controllers of such vehicles, are disclosed in Japanese Patent Laid-Open Nos. 1997-74710 and 1998-67243, Japanese Utility Model Laid-Open No: 1993-61432 and 1993-72544, and Japanese Patent Laid-Open No. 1997-329060.
The controller disclosed in Japanese Patent Laid-Open No. 1997-74710 is one where a differential gear mechanism which outputs driving force to at least two output shafts is linked to an internal combustion engine, first and second rotary motors are linked to the differential gear mechanism and either one of rotary shafts of the first and second rotary motors is inserted to the inside of the other motor so that the shaft rotates freely, to dispose the differential gear mechanism and both rotary motors on one and the same axis.
The invention disclosed in Patent Laid-Open No. 1998-67243 is a vehicle in which the driving force of an engine is transmitted to wheels via an automatic transmission and which is provided with an auxiliary driving source that is capable of driving wheels independently from the drive of the engine and control means which drives the other wheels by the auxiliary driving source when the engine stops.
One invention disclosed in Japanese Utility Model Laid-Open No. 1993-61432 is provided with electric generation control means and motor control means for controlling the rotary motor in a hybrid engine in which a rotary motor having power generating and motor functions is connected in parallel to a driving system of an internal combustion engine. The motor control means is provided with motor mode control means for setting drive assistance only for a predetermined period of time when the temperature is low and engine load setting means for setting engine output to supplement deficient output of the drive assisting amount.
One invention disclosed in Utility Model Laid-Open No. 1993-72544 is where an induction machine having motor and electricity generating functions is assembled to an engine of a crawler working vehicle and is provided with control means for supplying torque to the engine from the induction machine when output torque of the engine is large and for charging a battery by causing the induction machine to generate electricity with the extra torque when the output torque of the engine is small.
One invention disclosed in Japanese Patent Laid-Open No. 1997-329060 includes reflux control means for controlling an opening valve of reflux means so as to reflux exhaust gas to an intake pipe when fuel cut control is executed while operating an engine of a hybrid car.
As previously mentioned, in the prior art controllers of the so-called hybrid car, the engine control means and the motor control means exchange the operation data of the engine and the motor detected by the engine control means and the motor control means in driving the vehicle to control the operating conditions of the engine and the motor in coordination.
However, such vehicular controller has a problem that the control is complicated because the engine control means and the motor control means control in coordination with each other. Accordingly, such controller has had problems due to its complicated control process such that the reliability of the controller drops and costs increase.
In order to eliminate or minimize the above-mentioned problems, the present invention is characterized in that a vehicle is provided with an internal combustion engine, an electric motor which has driving and electric generating functions and is directly connected to the engine as a vehicle propulsion system, engine control means for controlling the operating condition of the engine, and motor control means for controlling the driving and power generating conditions of the motor based on the operating condition of the engine and the driving condition of the vehicle independently from the control of the engine by the engine control means.
Because the controller of the inventive vehicle propulsion system is provided with a motor, which has driving and electric generating functions and which is directly connected to the engine, engine control means for controlling the operating condition of the engine, and motor control means for controlling the driving and electric generating conditions of the motor based on the operating condition of the engine and the driving condition of the vehicle independently from the control of the engine made by the engine control means, the engine control means and the motor control means may be independent from each other and the engine and the motor may be controlled separately by the respective control means, thus simplifying the controller and its functions. It is noted that although the motor control means controls the motor without mutually exchanging its output with the engine control means, it shares a part of the input with the engine control means to detect the operating condition of the engine and the driving condition of the vehicle to utilize same for the control of the motor.